The related above cited invention is a method and apparatus for making fuel pellets directly from a log. The prior pellet manufacturing equipment for making pellets involved grinding sawmill residues and chips and compressing the ground materials at high pressures through extrusion dies. These extrusion mills are very expensive to operate and to build.
There is a need for a machine to convert logs, especially certain types of non-commercial hardwood directly into fuel pellets. The cost of construction and operation of such machines must be low compared to the extrusion mills. The veneer lathe type of machine in the parent related invention employs a peripheral log drive with at least three rolls which compress the log therebetween. The rolls have cutting surfaces to incise a shape into the surface of the log. The log is peeled with a veneer knife which cuts to a depth less than the incised depth. The veneer knife must be maintained in sharp condition in order to cleanly peel the log along the grain. If the knife loses its edge the power required to drive the log increases rapidly and the smoothness of the finished product diminishes.
It has been customary to immerse the logs to be peeled for the plywood in water for up to one month and to steam heat the log and its absorbed water immediately prior to peeling. It is believed that the absorbed water extends the life of the knife and serves as a lubricant as well as a coolant for the veneer knife. However, since product throughput i.e. production rate, is a most important factor, longer life knife edges are constantly being sought.
One of the major benefits of the peeling lathes are their ability to operate at high speeds. To sustain the highest speeds, it has been customary to use the highest grade tool steel for the veneer knives and to change out and sharpen the knives frequently as necessary. Most plywood facilities replace and refinish the veneer knives after four hours of use.
It is an object of this invention to reduce the downtime and cost of frequent veneer knife replacement and refinishing.
It is a further object of this invention to render the veneer knife self sharpening.
It is a still further object to provide an extremely long life veneer knife for pellet lathe devices.